Formation process of Sr-celsian from precursor zeolites

Abstract

Two kinds of zeolites with different crystal structures with the same chemical composition of SrO·Al2O3·2SiO2·xH2O prepared by an ion-exchange technique were used as a precursor of Sr-celsian. One was Sr-exchanged zeolite A (Sr-A), the other was Sr-exchanged Linde F zeolite (Sr-F). The Sr-A almost became an amorphous material at 400°C, and then generates a small amount of Sr-hexacelsian from the amorphous material at 500°C. The amount of Sr-hexacelsian steeply increased and a small amount of Sr-monocelsian also formed at 1000°C. On the other hand, the Sr-F nearly becomes an amorphous material at 300°C, and then Sr-hexacelsian mainly formed along with a small amount of Sr-monocelsian above 1000°C. In both of the Srexchanged zeolites, a single phase of Sr-monocelsian was obtained finally at 1300°C, owing to the hexacelsian -to -monocelsian phase transformation. The reason for the crystallization of Sr-hexacelsian at 500°C only from Sr-A was explained in terms of the similarity in framework structures of zeolite A and Sr-hexacelsian.

Sintering behavior of Ba/Sr celsian precursor obtained from zeolite‐A by ion‐exchange method

“…The thermal transformation of cation exchanged zeolites was then used in successive works to produce ceramics of high technological interest and specifically for the synthesis of the monoclinic polymorph of barium feldspar celsian …”